Expert Working Group for Pest Risk Analysis on Euphorbia davidii

Paris, 2025-02-17/20

In 2024, the Panel on Invasive Alien Plants identified Euphorbia davidii (Euphorbiaceae: EPPO List of Invasive Alien Plants), through the EPPO Prioritization Process for Invasive Alien Plants, as having a high spread potential and high impact and recommended the species for PRA. The Working Party on Phytosanitary Regulations approved their recommendation to carry out a PRA.

An Expert Working Group (EWG) was held at the EPPO headquarters in February 2025 to perform a Pest Risk Analysis on E. davidii for the EPPO region. E. davidii is an annual plant species that spreads locally by seed. It can form dense stands in agricultural areas. In the EPPO region there are observations of E. davidii infesting agricultural crops in France, Italy, Russia, Serbia and Uzbekistan, though quantitative evidence is lacking for negative impacts.

In total six experts attended the meeting from six countries (Argentina, Austria, the Netherlands, Russia, Serbia, the United Kingdom). This included four experts from the EPPO Panel on Invasive Alien Plants, an expert on species distribution modelling from Great Britain, and an expert on Euphorbia from Argentina: a country where the pest is invasive and where negative impacts have been reported on crop yields.

The EWG discussed the species’ biology and ecology, and conducted an analysis of the potential pathways for further entry into the EPPO region, including as a contaminant of grain and seed. The EWG discussed the potential establishment and spread of the species in the EPPO region, the impact of the species in Argentina and how these impacts may translate to the EPPO region, given a difference in agricultural practices between the regions. Finally, the EWG recommended measures to be taken against priority pathways to reduce the phytosanitary risk of the pest.

The outcome of the EWG, is a PRA that outlines that E. davidii has a high phytosanitary risk with a moderate uncertainty. This conclusion will be reviewed by the EPPO Core Members for PRA, the EPPO Panel on Invasive Alien Plants and the Working Party on Phytosanitary Regulations during 2025.